If a fluidized bed sand filter is properly designed, they last forever, are clog proof, are self-cleaning, and never need repair. The surface area of the sand is unmatched as well. There is also no other filter that can respond as rapidly to changes in bio-loads.
Fluidezed bed sand filters are not intended for clarifying of the water or any other "solids" removal. The sole problem I have found with a FBSF is if water flow is interupted for more than a few seconds without having a positive sealing check valve on the inlet side, re-starting is difficult.
These filters can't use ordinary sand and to operate properly the "sand" should be angular shaped and graded to near exact sizes and uniformity.
If people have problems with channeling or clogging, the chances are they are using the improper sand.
